>>Hi,
>>
>>A customer reported a problem where some of the emails sent by my ASP.NET application are rejected. The error message is:
>>

>>The server response was: 4.4.62 Mail sent to the wrong Office 365
>>

>>
>>I noticed that all emails that were rejected have a common domain. For example "@country.gov"
>>
>>I don't know how email servers work. But do you think the organization IT should whitelist this domain ("@country.gov") in the email server?
>
>This is one of the most frequent issues reported by clients. It's usually caused when the recipient's mail server has marked the sender as a spammer and is routing the email to a spam folder or just blocking it.

I hadn't seen Al's reply.
His makes sense.